Implantable medical devices are often used to treat a variety of medical conditions. Examples of implantable medical devices include drug delivery devices, pain management devices, and devices that treat heart arrhythmias. One example of an implantable medical device used to treat heart arrhythmias is a cardiac pacemaker, which is commonly implanted in a patient to treat bradycardia (i.e., an abnormally slow heart rate). A pacemaker includes a pulse generator and one or more leads, which form electrical connection(s) between the pulse generator and the heart. An implantable cardioverter defibrillator (ICD) may be used to treat tachycardia (i.e., an abnormally rapid heart rate). An ICD also includes a pulse generator and leads that deliver electrical energy to the heart.
Implantable medical devices are also useful in the treatment of heart failure. For example, cardiac resynchronization therapy (CRT) (also commonly referred to as biventricular pacing) is an emerging treatment for heart failure, which involves stimulation of both the right and left ventricles to increase hemodynamic efficiency and cardiac output. In some cases, the treatment of heart failure and heart arrhythmias can be enhanced through the use of implanted sensors. In some systems, for example, a pressure sensor implanted within a chamber of the heart or in a body vessel such as an artery or vein can be used to sense blood pressure, which can be used to compute cardiac output, pulmonary vascular resistance, as well as other hemodynamic parameters. The sensor data from the sensor can be downloaded by a clinician and can be used to modify the therapy delivered by the implantable medical device.